thanks for adding your article Jim - very interesting - although I'm sorry to hear that the lamp cup has some damage, and as someone who has a particular liking for C19 pieces, I very much envy you this item.
May I add a few comments regarding the more entomological side of the story. As you say, in the U.K. we have only a very few species of hawkmoth (in comparison with the rest of the warm world) - of which the rarer non-resident ones do indeed include the Oleander Hawk Moth, possibly one the rarest migrant species of lepidoptera to reach our shores. Certainly the image on the lamp is of course simply an extremely stylized picture of a moth - and if you look at C18 and C19 ceramics, there are many examples of flying insects depicted, most of which owe nothing to the real world, rather more to a need for something colourful and exotic looking. As a general rule, moths have fine thread like antennae - whereas the antennae of butterflies end in a club like lump. Annoyingly, there are exceptions - some moths have club like antennae - some moths fly in the daytime - and we even have two hawk moths (in the U.K.) that mimic bees and fly in the daytime.
The illustration that you show in your article appears to represent quite accurately another of the very rare migrant species - the Spurge Hawk Moth - not the Oleander Hawk (which is predominantly varous shades of green), whereas the Spurge is various shades of pink and brown (as in your picture). The two species look absolutely nothing like each other - so there shud not be any confusion - and the reference to Oleander may well be simply because the Oleander is a hawk that, on the Continent, eats vinca spp. In the world of moths, many species of larvae are quite literally omnivorous, and I dare say wud be more than happy to settle for a salad of periwinkle (and some species do indeed actually even eat their own brothers and sisters if the green stuff gets a bit scarce!)
I was surprised to read from Christine that periwinkle was non-native - when did the plant first come to this country?
Paul S.